1. Field of the Invention
The present invention relates to a cable-type steering device, including a wire driving means connected to a steering wheel, and a wire follower means connected to a gear box for steering vehicle wheels. The wire driving means and the wire follower means are connected to each other by wires, so that a steering torque inputted to the steering wheel is transmitted to the gear box through the wires.
2. Description of Related Art
In a conventional steering device for a vehicle, a steering shaft having a steering wheel at an upper end thereof is connected at its lower end to a gear box, so that a steering torque inputted to the steering wheel is transmitted through the steering shaft to a rack and pinion mechanism which is mounted within the gear box.
However, if the steering wheel and the gear box are connected to each other using the steering shaft, it is difficult to freely select the position of the steering wheel relative to the position of the gear box. For this reason, there is encountered a problem that the degree of freedom of design is substantially limited, and the gear box can not be commonly used in a right-hand steered vehicle and a left-hand steered vehicle. Moreover, another problem is that vibrations inputted to a tire from a road surface and the vibration of an engine are transmitted to the steering wheel through the steering shaft and hence, the sound level within a vehicle compartment and the riding comfort are impeded by such vibrations.
Therefore, there is, a proposed cable-fype steering device which employs a flexible transmitting means such as Bowden wire, and the like in place of the conventional steering shaft. (see Japanese Patent Application Laid-open No.8-2431).
If the construction of the proposed cable-type steering device is used, the position of the steering wheel retentive to the position of the gear box can be freely selected and moreover, the vibration of the gear box is not readily transmitted to the steering wheel and hence, the above-described problems can be solved.
When such cable-type steering device is combined with an electric power-steering device, the following problem is encountered: there are required a steering torque transmitting system for transmitting a steering torque provident by the cable-type steering device to vehicle wheels, for example, through a rack and pinion mechanism, and a steering torque transmitting system for transmitting a steering torque provided by a motor of the power-steering device to the vehicle wheels, for example, through a ball screw mechanism. These two steering torque transmitting systems require a complicated structure and cause a loss in transmission of the steering torque.